This paper contributes to the literature on the weakness of modern pay-as-yougo social security systems in financing pensions by taking a business and economic historical perspective on the issue. It focuses on Prussian Knappschaften (plural of Knappschaft), which provided miners with compulsory invalidity and implicit old-age insurance, and studies the period from 1854 to 1913. Knappschaften used the pay-asyou-go mechanism, and, in the long-term, came under financial pressure by the rising number of pensioners. The question to be answered is whether Knappschaften were able to offer cohorts of miners entering the system at different times the same implicit rates of return. Did Knappschaften provide an intergenerationally sustainable policy, or did adjustments of contributions and other parameters decrease the dividend for insured miners over time?